I don't know the demographics on that, do women make up a significantly bigger percentage of competitive ultimate than competitive disc golf?

I'd venture a guess of hell yes. Ultimate is a team/social sport where communication is part of the game and people are always around. Most women prefer this type of environment compared to a more loner sport like disc golf where you get chastised for talking too much and go out into the woods with strange men.

Ultimate seems more like Rugby to me. Rugby with frisbees would be pretty awesome.

Or soccer.

In the 1980s we "invented" Ultimate independently. Just as people threw Frisbees at trees, we started to play Frisbee Football and were quickly bored, and the Ultimate concept is very simple. We played a lot of it, sometimes 2-on-2 or 3-on-3, which involves a LOT of running. For reasons forgotten, it struck us as being like rugby, and we called it "frugby".

Which might sound really stupid, or even frolfy, but if we'd realized it was more like soccer we'd have been calling it "froccer" or "sugby", words that should be pronounced carefully in polite society.

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I don't know if Ultimate has greater female participation in competitive play or not. But as a team sport, it has the opportunity to require co-ed teams, which would affect the balance.

Two of my coworkers at my old job were as big into ultimate as I am into disc golf. They would travel cross country for team tournaments; a lot of their teammates went to a tournament in Italy. People take it very, very seriously.

I also know they played in a mixed league - lots and lots of female players. Lots.